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BM40A1500 Data Structures and Algorithms/Assignments/Week 5/bintree.py

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+class Node:
+    def __init__(self, key):
+        self.key = key
+        self.left = None
+        self.right = None
+
+
+class BST:
+    def __init__(self):
+        self.root = None
+
+    def insert(self, key):
+        if self.root is None:
+            self.root = Node(key)
+        else:
+            self._insert(self.root, key)
+
+    def _insert(self, node, key):
+        if key < node.key:
+            if node.left is None:
+                node.left = Node(key)
+            else:
+                self._insert(node.left, key)
+        elif key > node.key:
+            if node.right is None:
+                node.right = Node(key)
+            else:
+                self._insert(node.right, key)
+
+    def search(self, key):
+        if self.root is None:
+            return False
+        else:
+            return self._search(self.root, key)
+
+    def _search(self, node, key):
+        if node is None:
+            return False
+        elif node.key == key:
+            return True
+        elif key < node.key:
+            return self._search(node.left, key)
+        else:
+            return self._search(node.right, key)
+
+    def preorder(self):
+        if self.root is None:
+            return
+        else:
+            self._preorder(self.root)
+        print()
+
+    def _preorder(self, node):
+        if node is None:
+            return
+        print(node.key, end=" ")
+        self._preorder(node.left)
+        self._preorder(node.right)
+
+    def breadthfirst(self):
+        if self.root is None:
+            return
+        else:
+            self._breadthfirst(self.root)
+        print()
+
+    def _breadthfirst(self, node):
+        if node is None:
+            return
+        queue = []
+        queue.append(node)
+        while len(queue) > 0:
+            print(queue[0].key, end=" ")
+            node = queue.pop(0)
+            if node.left is not None:
+                queue.append(node.left)
+            if node.right is not None:
+                queue.append(node.right)
+
+    def remove(self, key):
+        if self.root is None:
+            return
+        else:
+            self._remove(self.root, key)
+
+    def _remove(self, node, key):
+        if node is None:
+            return node
+        if key < node.key:
+            node.left = self._remove(node.left, key)
+        elif key > node.key:
+            node.right = self._remove(node.right, key)
+        else:
+            if node.left is None:
+                temp = node.right
+                node = None
+                return temp
+            elif node.right is None:
+                temp = node.left
+                node = None
+                return temp
+            temp = self._minValueNode(node.right)
+            node.key = temp.key
+            node.right = self._remove(node.right, temp.key)
+        return node
+
+    def _minValueNode(self, node):
+        if node is None:
+            return node
+        while node.left is not None:
+            node = node.left
+        return node
+
+
+if __name__ == "__main__":
+    Tree = BST()
+    keys = [5, 9, 1, 3, 7, 4, 6, 2]
+    for key in keys:
+        Tree.insert(key)
+
+    Tree.preorder()         # 5 1 3 2 4 9 7 6
+    Tree.breadthfirst()    # 5 1 9 3 7 2 4 6